According to ARY News, suspects Saeed Baloch, Saleem Deedag, Mahar Bux and Dil Murad were arrested from Kalri police precinct in Lyari area of Karachi.
The investigation sources said that the accused have confessed to give money to political personalities from Lyari and Keamari.
During questioning the accused have also confessed to having funded outlawed Peoples Amn Committee and the proscribed Balochistan Liberation Army (BLA) for a long time, investigation sources said.
According to media reports Saeed Baloch has been general secretary of Pakistan Fisherfolk Forum and his family has claimed that he went missing on Jan 16 and was in Rangers custody.
The Rangers spokesman however in a statement said that the suspects were taken into custody on Monday from Kalri locality of Lyari upon receiving credible information about their alleged involvement in extortion and other offences.
The family of Saeed Baloch had recently filed a petition in the Sindh High Court regarding his illegal detention. The petitioner said that Baloch along with Mahar Bux and Dil Murad had been in the unlawful detention of the Rangers since Jan 16 and pleaded to the court to declare the detention as illegal and unauthorised.